An interesting exercise that could be effective. You need to avoid contacting elbows with pads. The photo of Larry doing extensions is not a good example. Keep your elbows beyond the edge of the pads to avoid damaging the delicate sheath that covers the elbows. Once damaged they can be sore for years and years afterwards. I might build a shortened pad for this exercise and let the lads in my gym try it out. An adjustable standing bench might be interesting, too.